[PATCH v3 4/6] ubsan: Check panic_on_warn

Kees Cook
2020-01-16T01:24:31Z

Syzkaller expects kernel warnings to panic when the panic_on_warn
sysctl is set. More work is needed here to have UBSan reuse the WARN
infrastructure, but for now, just check the flag manually.

Link: https://lore.kernel.org/lkml/CACT4Y+bsLJ-wFx_TaXqax3JByUOWB3uk787LsyMVcfW6JzzGvg@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
lib/ubsan.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/lib/ubsan.c b/lib/ubsan.c
index 7b9b58aee72c..429663eef6a7 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -156,6 +156,17 @@ static void ubsan_epilogue(void)
"========================================\n");

current->in_ubsan--;
+
+ if (panic_on_warn) {
+ /*
+ * This thread may hit another WARN() in the panic path.
+ * Resetting this prevents additional WARN() from panicking the
+ * system on this thread. Other threads are blocked by the
+ * panic_mutex in panic().
+ */
+ panic_on_warn = 0;
+ panic("panic_on_warn set ...\n");
+ }
}

static void handle_overflow(struct overflow_data *data, void *lhs,
--
2.20.1